From 297b71efcfdda2d878dbc958932083ed5c0a2296 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Sat, 10 Nov 2018 17:10:30 -0800
Subject: [PATCH] Concepts usage improved

---
 src/include/units/bits/stdconcepts.h | 20 ++++++++------------
 src/include/units/bits/tools.h       |  2 +-
 src/include/units/quantity.h         |  2 +-
 src/include/units/si/frequency.h     | 14 ++------------
 src/include/units/si/length.h        | 14 ++------------
 src/include/units/si/time.h          | 13 ++-----------
 src/include/units/si/velocity.h      | 14 ++------------
 7 files changed, 18 insertions(+), 61 deletions(-)

diff --git a/src/include/units/bits/stdconcepts.h b/src/include/units/bits/stdconcepts.h
index 12ff750e..7a60a0e5 100644
--- a/src/include/units/bits/stdconcepts.h
+++ b/src/include/units/bits/stdconcepts.h
@@ -29,19 +29,15 @@ namespace mp {
 
   namespace std_concepts {
 
-    namespace detail {
-      template<class T, class U>
-      concept bool SameHelper = std::is_same_v<T, U>;
-    }
+    template<typename T, typename U>
+    concept bool Same = std::is_same_v<T, U>;
 
-    template<class T, class U>
-    concept bool Same = detail::SameHelper<T, U>&& detail::SameHelper<U, T>;
-
-    template<class From, class To>
-    concept bool ConvertibleTo = std::is_convertible_v<From, To>&& requires(From (&f)())
-    {
-      static_cast<To>(f());
-    };
+    template<typename From, typename To>
+    concept bool ConvertibleTo =
+      std::is_convertible_v<From, To> &&
+      requires(From (&f)()) {
+        static_cast<To>(f());
+      };
 
   }  // namespace std_concepts
 }  // namespace mp
diff --git a/src/include/units/bits/tools.h b/src/include/units/bits/tools.h
index 516ca3ff..3bf4e09e 100644
--- a/src/include/units/bits/tools.h
+++ b/src/include/units/bits/tools.h
@@ -32,7 +32,7 @@ namespace units {
 
   template<typename T>
   concept bool Number = requires(T a, T b) {
-    { a + b} -> T;
+    { a + b } -> T;
     { a - b } -> T;
     { a * b } -> T;
     { a / b } -> T;
diff --git a/src/include/units/quantity.h b/src/include/units/quantity.h
index c8b3cd54..9f7a0448 100644
--- a/src/include/units/quantity.h
+++ b/src/include/units/quantity.h
@@ -48,7 +48,7 @@ namespace units {
 
   // treat_as_floating_point
 
-  template<class Rep>
+  template<typename Rep> // todo Conceptify that
   inline constexpr bool treat_as_floating_point = std::is_floating_point_v<Rep>;
 
   // quantity_cast
diff --git a/src/include/units/si/frequency.h b/src/include/units/si/frequency.h
index b7d972a5..0d27b3a1 100644
--- a/src/include/units/si/frequency.h
+++ b/src/include/units/si/frequency.h
@@ -36,21 +36,11 @@ namespace units {
   using gigahertz = unit<dimension_frequency, std::giga>;
   using terahertz = unit<dimension_frequency, std::tera>;
 
-  template<Unit U = hertz, typename Rep = std::intmax_t>
+  template<Unit U = hertz, Number Rep = std::intmax_t>
   using frequency = quantity<dimension_frequency, U, Rep>;
 
-  namespace detail {
-
-    template<typename T>
-    struct is_frequency : std::false_type {};
-
-    template<Unit U, typename Rep>
-    struct is_frequency<frequency<U, Rep>> : std::true_type {};
-
-  }
-
   template<typename T>
-  concept bool Frequency = detail::is_frequency<T>::value;
+  concept bool Frequency =  Quantity<T> && Same<typename T::dimension, dimension_frequency>;
 
   // ...
 
diff --git a/src/include/units/si/length.h b/src/include/units/si/length.h
index e4ce39e6..de31b55c 100644
--- a/src/include/units/si/length.h
+++ b/src/include/units/si/length.h
@@ -34,21 +34,11 @@ namespace units {
   using meter = unit<dimension_length, std::ratio<1>>;
   using kilometer = unit<dimension_length, std::kilo>;
 
-  template<Unit U = meter, typename Rep = std::intmax_t>
+  template<Unit U = meter, Number Rep = std::intmax_t>
   using length = quantity<dimension_length, U, Rep>;
 
-  namespace detail {
-
-    template<typename T>
-    struct is_length : std::false_type {};
-
-    template<Unit U, typename Rep>
-    struct is_length<length<U, Rep>> : std::true_type {};
-
-  }
-
   template<typename T>
-  concept bool Length = detail::is_length<T>::value;
+  concept bool Length = Quantity<T> && Same<typename T::dimension, dimension_length>;
 
   namespace literals {
 
diff --git a/src/include/units/si/time.h b/src/include/units/si/time.h
index de7f1955..41ec3353 100644
--- a/src/include/units/si/time.h
+++ b/src/include/units/si/time.h
@@ -36,21 +36,12 @@ namespace units {
   using minute = unit<dimension_time, std::ratio<60>>;
   using hour = unit<dimension_time, std::ratio<3600>>;
 
-  template<Unit U = second, typename Rep = std::intmax_t>
+  template<Unit U = second, Number Rep = std::intmax_t>
   using time = quantity<dimension_time, U, Rep>;
 
-  namespace detail {
-
-    template<typename T>
-    struct is_time : std::false_type {};
-
-    template<Unit U, typename Rep>
-    struct is_time<time<U, Rep>> : std::true_type {};
-
-  }
 
   template<typename T>
-  concept bool Time = detail::is_time<T>::value;
+  concept bool Time = Quantity<T> && Same<typename T::dimension, dimension_time>;
 
   // ...
 
diff --git a/src/include/units/si/velocity.h b/src/include/units/si/velocity.h
index 3d153b8e..adb6ca67 100644
--- a/src/include/units/si/velocity.h
+++ b/src/include/units/si/velocity.h
@@ -34,21 +34,11 @@ namespace units {
   using kilometer_per_hour = unit<dimension_velocity, std::ratio<1000, 3600>>;
   using mile_per_hour = unit<dimension_velocity, std::ratio<44'704, 100'000>>;
 
-  template<Unit U = meter_per_second, typename Rep = std::intmax_t>
+  template<Unit U = meter_per_second, Number Rep = std::intmax_t>
   using velocity = quantity<dimension_velocity, U, Rep>;
 
-  namespace detail {
-
-    template<typename T>
-    struct is_velocity : std::false_type {};
-
-    template<Unit U, typename Rep>
-    struct is_velocity<velocity<U, Rep>> : std::true_type {};
-
-  }
-
   template<typename T>
-  concept bool Velocity = detail::is_velocity<T>::value;
+  concept bool Velocity = Quantity<T> && Same<typename T::dimension, dimension_velocity>;
 
   // ...